1. Field of the Invention
This invention broadly relates to a dental syringe for dispensing air and/or water during dental procedures. More particularly, the invention relates to a dental air-water syringe having a replaceable device for purifying water flowing through the syringe.
2. Description of the Related Art
Hand-held syringes that dispense air and water are commonly used during many dental procedures. For example, compressed air dispensed from dental air-water syringes is often used to dry the patient's tooth structure such as the dentin or enamel. Many dental compositions do not bond strongly to tooth structure if water is present. The application of compressed air to the tooth surface provides a convenient, inexpensive means to assure that the tooth structure is essentially free of moisture so that a strong bond between the composition and the tooth structure is developed.
Water is often dispensed from dental air-water syringes to clean debris and other foreign matter that may be present in the oral cavity. As an example, a spray of water can be utilized to clean tooth structure that is to be subsequently dried by compressed air before ultimately receiving a dental material such as a restorative or the like. A spray of water in the patient's oral cavity can also help to eliminate objectionable odors during the dental procedure.
Dental syringes are typically connected to a source of air and a source of water by flexible tubing having separate air and water conduits. The tubing is often relatively long and has a relatively small cross-sectional area in order to allow the syringe to be held in a number of different orientations and facilitate maneuverability of the tip of the syringe in the oral cavity as may be needed.
Unfortunately, it has been found that film-like growths of microorganisms, also known as biofilms, are often present in large concentrations in the water conduit of the flexible tubing connected to dental air-water syringes. Such biofilms are microbial populations that typically include bacteria, fungi and protozoa that form on the inner surfaces of the small-diameter water conduit. Water flowing through the water conduit may pick up and transport microorganisms from the biofilm and consequently develop a bacterial count significantly higher than a bacterial count that is considered normally acceptable for potable water.
Water having a high bacterial count that is dispensed from dental air-water syringes is a cause for concern for both dental patients and dental staff, particularly if the patient or staff member has a relatively weak immune system. For example, many dental procedures may cause bleeding in the patient's oral cavity, and such bleeding increases the risk that bacteria from the biofilm will enter the patient's blood stream. The dental staff may also be exposed to risk of infection because the bacteria-laden water discharged from the syringe may disperse into the atmosphere as an aerosol and then inhaled.
A number of suggestions have been made in the past to reduce microbial population counts in water dispensed from dental instruments including air-water syringes and dental handpieces. One such suggestion concerned a filter having relatively small openings through which the water must pass before being dispensed from a syringe. An example of such a filter is described in U.S. Pat. No. 5,204,004 and includes a microporous membrane having a porosity that blocks the passage of particulate matter having a diameter larger than about 0.2 microns.
Another approach to reducing microbial population counts in water dispensed from dental instruments involves the use of disinfectant media. For example, U.S. Pat. No. 5,474,451 describes dental water dispensing instruments that include a disinfectant media held on a support. This patent describes media comprised of multi-valent iodine resin, as well as media made of a multi-valent iodine resin with bromide, a bromide derivative particulate, quantenary ammonium-silver-chlorine-bromine-bromide bearing medias, and other halogen resins or halogen derivatives.
Another method to reduce microbial population counts in water dispensed from dental instruments involves the use of chemical disinfection wherein a liquid that includes a chemical disinfectant is introduced into the instrument. As one example, the water passageways in the flexible tubing interconnecting the instrument and a source of water may be filled with a disinfectant solution that resides in the water conduit for about 10 minutes. The chemical disinfectant is then purged by tap water from the passageways prior to use of the instrument for dental applications. As another example, a dental instrument is connected to a source of disinfectant solution, and small but measurable amounts of the disinfectant solution are released into the water solution and are present in the discharged water.
Devices for reducing microbial population counts in water dispensed from dental air-water syringe water lines, including the devices described above, are often attached to the flexible tubing that interconnects the syringe to the source of water. The device described in U.S. Pat. No. 5,204,004, for example, is interposed in the flexible tubing through the use of Luer fittings. Unfortunately, such an arrangement may not satisfactorily reduce the amount of biofilm that may ultimately develop in areas downstream of the device including in areas of the various passages within the syringe.
Other suggestions in the past have included water purification devices that are connected directly to the air-water syringe. For example, U.S. Pat. No. 5,474,451 describes in certain embodiments a purifying device that is connected to a hand piece of a dental air-water syringe and in other embodiments a purifying device that is connected to a tip of the dental air-water syringe. Both such concepts are advantageous over the previously mentioned approach, in that the purifying device is relatively close to the location where the water is dispensed from the syringe and is downstream of the flexible tubing that interconnects the syringe and the source of water.
However, there remains a need in the art for a dental air-water syringe with a water purifying device that enhances maneuverability of the syringe tip in the patient's oral cavity. Preferably, the tip of such an air-water syringe would be readily detachable from the hand piece of the syringe for disposal and replacement or re-sterilization. Moreover, the water purifying device of such a syringe preferably would be relatively inexpensive in order to enhance the economic feasibility of disposing of the device after use on a single patient.